In recent years, the media industry has adopted digital technologies to record and play numerous types of media, such as audio, still photographs, and moving video. The use of digital video has become increasingly prevalent in today's society. This phenomenon is not without warrant, as digital video provides numerous advantages over analog video. As users of the popular DVD format well know, digital video does not degrade from repeated use. Digital video can also either be delivered for presentation all at once, as when loaded by a DVD player, or delivered in a stream as needed. Today, digital media systems are available to deliver and present digital content to viewers in increasing numbers. However, the digital content needed to develop and test these digital media systems is in short supply.
Digital video is often first recorded in traditional analog form. It is encoded, or digitized, and compressed into a digital format that can be stored on disk and decoded during playback. For example, using techniques well understood by those in the art, a show broadcast over analog television may be converted into a digital format by using a device called an encoder.
However, while the practice of converting analog video presentations into digital form may be well understood, it is not practical for either testing or commercial purposes. The intellectual property rights of the original owners of the analog video must be respected, and only those individuals who have obtained the rights to the analog media presentation are authorized to use the converted digital presentation for private use.
During testing of a digital media system, it is necessary to have ample amounts of digital video to sufficiently test all components of the digital media system. Prior attempts to generate substantial amounts of digital content to facilitate system testing have met with limited success. As mentioned earlier, digitalizing analog video is cost prohibitive, due to the licensing of intellectual property. Also, as it was not originally contemplated for digital presentation, the content available in analog broadcasts is neither well suited nor of sufficient complexity to test the performance of a digital media system. Further, testing features such as fast forward or rewind is difficult at best without specific temporal information visible in the presentation. Such temporal information may include the time the presentation was encoded, the time the presentation was delivered by the server, and the time the presentation was received by the client. Without such information, it is difficult to determine the accuracy of a fast forward or rewind operation, or the lag time in the digital media system when delivering frames of video.
Content for digital media testing also needs to conform to certain standards. One popular standard for digital media is DVB, or Digital Video Broadcasting. DVB is a set of standards for transmitting compressed digitized video over broadcast industry transmission channels, such as cable, satellite, or terrestrial transmissions. Further information about the DVB standard may be obtained at the Internet web address “www.dvb.org”. ATSC is another standard for transmitting video that is used primarily in digital high definition television (HDTV), standard definition television (SDTV), data broadcasting, multi-channel surround-sound audio, and satellite direct-to-home broadcasting. Further information on the ATSC standard may be found at the Internet web address “www.atsc.org”.
Analog video may be encoded, or digitized, into a digital format conforming to the above standards through the use of an encoder. The set of standards that may be selectively implemented by the encoder during the digitization process are not limited to the above examples, and may include other standards such as MPEG-1, MPEG-2, real player, or AVI. As there are numerous digital media standards, and that number will likely only grow in the coming years, the need to generate content for a digital media system conforming to a variety of format standards will accordingly grow.
Current methods of generating test content for a digital media system have not met the needs of designers and testers of digital media systems. For example, one common method for generating a suite of test content involves the recording of original analog video, often time something as mundane as a stationary clock, with a standard VHS video recorder, and digitizing the resulting analog recording into a digital format. While this method does not require the licensing of intellectual property, as digitizing a segment of broadcast television would, it is still riddled with problems. First, as with any digitized analog recording, the cause of any fluctuation in the quality of digital video presentation cannot be isolated to the digital media system, as the problem could have arisen in the quality of the original analog video. Second, digital test content should test the constraints of the digital media system by being rich in color, sound, and moving objects. Such conditions are impractical to record in real life with a standard VHS video recorder. Third, without information identifying each frame of digital video, it is difficult to test scan operations as well as isolating delays in the digital media system in presenting digital video. While content in the video, such as the clock face, can be used to generally determine that a fast forward or rewind operation worked, it does not provide any frame specific information which is needed to accurately determine the success of a jump in time or isolate delays in presentation throughout the digital media system.
Another approach in obtaining test content is to use a selection of pre-generated digital samples, such as those available on the Internet. However, in addition to encountering the problems mentioned above of licensing intellectual property, and lacking frame specific information, these selections are typically of extremely short duration, which severely restricts their value in testing. Further, a suite of testing content should as much as possible exhaustively cover all the possible real world scenarios, which the small samplings of digital video available do not begin to address. Without varying the content in the digital content samples in the test suite, it is difficult to ensure that the full spectrum of problems that a digital video server may encounter have been tested. Additionally, each of these selections of pre-generated digital samples is fixed in one digital format, and will not serve the need to test multiple digital formats.
Given the inefficiencies of the current method of digital content generation and testing, there has been a long felt need, therefore, for a method or apparatus for generating original digital content that addresses the above needs for testing a digital media system. Such a method or system should allow one to configure the content of the digital video to test all components of the digital video system as well as encode the digital video in a variety of digital formats.